eye+ear

Light rays are refracted when:

(1) They pass between two media of different densities (2) These media meet at a curved surface

production of aqueous humor

-It is continuously produced by the ciliary processes. ----The circulation of aqueous humor provides nutrients and oxygen to both the avascular cornea and the lens

Age-related macular disease (AMD)

-also known as macular degeneration -In AMD, abnormalities occur in the region of the macula lutea, which is ordinarily the area of most acute vision

Before light can reach the photoreceptor cells, it must pass from the air through the

1.Cornea 2.Aqueous humor 3.Lens 4.Vitreous humor 5.Cells forming the inner layers of the retina

Angle-closure glaucoma

1.a direct consequence of the narrowing of this angle consists about one-third of all cases of glaucoma

Open-angle glaucoma accounts

1.for about two-thirds of glaucoma cases. In the drain angles are adequate but fluid transport out of the anterior chamber is impaired

Congenital glaucoma

1.occurs only rarely and is due to hereditary factors or intrauterine infection

The relative tension in the suspensory ligaments is altered by

1.relaxation and contraction of the ciliary muscles in the ciliary body

pupil dilation

Dilator pupillae sympathetic

The eye is spherical, measuring about

The eye is about 2.5 cm

characteristics of rods

They function well in dim light. There are more than 100 million rod cells per eye.

The lens is

a transparent, biconvex structure, composed of precisely arranged layers of cells that have lost their organelles and are filled completely by a protein called crystallin.

Retina (inner layer)

a)Pigmental layer b)Neural layer

sphincter pupillae muscle

a)is arranged in concentric circles around the pupil. This muscle contracts when stimulated by parasympathetic division through the oculomotor nerve (CN III).

Which cavity of the eyeball is divided into an anterior and posterior chamber

anterior cavitity

What type of fluid is found in the anterior cavity of the eyeball

aqueous humor

The most visible part of the external ear is called the

auricle or pinna

Gustatory cells are

chemoreceptors

What is the largest structure of the vascular tunic

choroid

What structure is filled with pigment from melanocytes

choroid

Which structure of the eye absorbs light to prevent it from scattering within the eye

choroid

Vascular tunic (middle layer)

choroid, ciliary body, iris

The iris is continuous with the

ciliary body

suspensory ligaments attach the lens to

ciliary muscle

Sensory receptors

components of the nervous system that provide us with information about our external and internal environments.

What type of photoreceptors detects color

cones

As we adjust to low light, our ______ becomes nonfunctional and it may take ______ for rhodopsin to become regenerated sufficiently so that you can see well in low-light conditions.

cones; 20-30 minutes

Closer objects less than 20 feet, the ciliary muscles

contract

transducers

convert stimulus energy into electrical energy

The limbus is the junction between

cornea and sclera

When you go from a bright light environment to a dark environment, you have a slow sensitivity to low light levels. This is called

dark adaption

lens shape determines

degree of light refraction

Light rays are refracted or bent when they pass through two media of different

densities

Cutaneous receptors are a type of

exteroceptors

The external layer of the eye wall is the

fibrous tunic

The eyeball contains two tunics

fibrous tunic and vascular tunic

the center of the macula lutea is the

fovea centralis

the portion of the retina that is predominantly composed of cones and provides the sharpest vision

fovea centralis

Where do the fibers of the optic nerve come from?

from the axons of the ganglion cells

Where are photoreceptors located

in the neural layer of the retina

When the photoreceptors stop _____________ the bipolar cells, the bipolar cells can then release their neurotransmitter that binds to receptors on the ganglion cells.

inhibiting

The segment of the photoreceptors that connects directly to the cell body is the

inner segment

The segment of each photoreceptor that contains organelles for the cell such as mitochondria is the

inner segment.

The retina is the ______ layer of the eye wall.

internal

The most anterior region of the vascular tunic is the

iris

What structure is the dividing line between the anterior and posterior chambers

iris

vitreous humor

is a transparent, gelatinous fluid that completely fills the posterior cavity.

Aqueous humor

is a transparent, watery fluid that circulates within the anterior cavity.

The sclera

is made of dense connective tissue provides for eye shape

Dilator pupillae muscle

is organized in a radial pattern through the iris. This muscle contracts when stimulated by the sympathetic division.

the posterior and anterior cavities are separated by the

lens

The posterior cavity

lies behind the lens, contains a permanent fluid called vitreous humor.

The process by which your eyes adjust from low light to bright light conditions is

light adaption

The exact center of the retina is the

macula lutea.

Tactile receptors are a type of

mechanoreceptor

The optic (II) nerve is also visible located

medially from the fovea centralis

The optic disc contains ______ photoreceptors

no

The optic disc contains ______ photoreceptors.

no

Referred pain

occurs when impulses from an organ are perceived as originating from the skin

A lack of photoreceptors in this structure creates the "blind spot"

optic disc

The point at which the optic nerve exits the eye is the

optic disc (blind spot)

The fat surrounding the eye is called

orbital fat

The segment of each photoreceptor that is composed of hundreds of discs containing photopigments that are capable of absorbing light energy is the

outer segment

The sphincter pupillae is controlled by the ______ division of the nervous system

parasympathetic

If stimulated over a period of time receptors eventually lose sensitivity

phasic

What type of receptor can undergo adaptation

phasic

In phototransduction, the ____________ responds to light stimulation by changing its resting membrane potential, resulting in a change in the neurotransmitter it releases.

photoreceptor

The process by which photoreceptors become activated when the photopigments are altered by light entering the eye is

phototransduction

Each type of photoreceptor has an outer segment that extends into the

pigmented layer of the retina.

The retina lines the

posterior 3/4 of inner layer of eyeball

The iris controls the size of the

pupil

aqueous humor moves from the posterior chamber through the

pupil and to the anterior chamber

Which events occur during bright light adaptation

pupils constrict cones gradually adjust rods become inactive

The apparent distortion of the spoon in the water glass is due to the phenomenon called

refraction

When we view objects greater than 20 feet away, the ciliary muscles

relax

The most internal layer of the eye wall is the

retina

What structure makes up the posterior 5/6 of the fibrous tunic

sclera

Which part of the eye is an attachment site for extrinsic eye muscles

sclera

fibrous tunic (outer layer)

sclera and cornea

excess aqueous humor is reabsorbed into the

scleral venous sinus

Receptors for general senses are usually

simple in structure

pupil constriction

sphincter pupillae parasympathetic

The general function of all sensory receptors is to detect and respond to a

stimulus

Optic tracts extend to which structures after they leave the optic chiasm

superior colliculi the lateral geniculate nucleus of the thalamus

The lens is held in place by the

suspensory ligaments

Mechanoreceptors located in the skin and mucous membranes are called

tactile receptors

the vascular tunic is composed of

the choroid, ciliary body (both the ciliary processes and ciliary muscle), and iris.

The process is called accommodation and is controlled by

the parasympathetic within the oculomotor nerve (CN III).

the retina is composed of

the pigmented layer and neural layer (the layer containing the visual receptors)

The interior of the eye consists of two fluid-filled cavities

the posterior cavity and the anterior cavity

the fibrous tunic is composed of

the sclera and the cornea

when ciliary muscles contract

the tension on the suspensory ligaments decreases and the lens can become more spherical.

when ciliary muscle relaxes

the tension on the suspensory ligaments increases and causes the lens to flatten

The primary purpose of the eyebrows is

to keep sweat out of the eyes.

The suspensory ligaments attach to the lens capsule at its periphery, where they

transmit tension that enables the lens to change shape

characteristics of the cornea

transparent and avascular

The vascular tunic of the eye is also called the

uvea

The middle tunic of the eye wall is the

vascular tunic

An ophthalmoscope is used to

view the retina through the pupil.